Transformer



I/ Feb. 1, 1927.

Filed Oct.

W. J'. SHACKELTON TRANSFORMER Passed Feb. 1,1927.

`UNITED STATI-:s YPATENT orifice.

WILLIAM J. SHACKELTON, F SCOTCH PLAINS, NEW JERSEY, ASSIGNGR T0 WESTERN ELECTRIC COMPANY, INCORPORATED, 0F NEW "YORK, N. Y., A CORPORATION 0F lIN' EW YORK.

TRANSFORMER.

p This invention relates to transformers and balanced amplifier vcircuits employing them. An object of this invention is to reduce transient voltage eifects -in signaling ycircuits employing transformers, particularly, electric discharge device output transformer circuits.

Another object of this invention is to preventasudden current change in a transformer winding from building up a transient voltage effect of a magnitudev appre- .ciabl'y greaterthan the normal operating voltage impressed thereon.

Another object yof this invention is to reduce the tendency of `a push pull amplifier to sing.

In accordancewith the form of this invention hereinafter described in detail, these objects are accomplished by an embodiment of this invention applied as an out-put transformer for a push-pull repeater circuit. ln such a type of circuit it is customary to connect the negative terminal of the output circuit battery to the two cathodes of the tubes arranged in push-'pull relation, the

positive terminal of the source being connectedto `the mid-point of the primary winding of the output transformer, the two outside terminals of the primary winding bein connected respectively to the two ano es of the tubes. Certain types of output transformers hitherto employed in pushpull circuits have in the normal operation of the circuitlbeen subjected to high tran- -fi sient voltages,I due in part atileast, to leakage reactance betweenditferent parts of the transformer primary winding. This leakage reactance acts 'as a separate inductance element so that dangerous transient voltages 40 may be produced at its terminals by a sudden change in the current therethrough. In

addition this leakage reactance tends to produce parasitic oscillations. Leakage inductance introducedin the input circuit has 46 a similar effect in roducing oscillations.

`In accordance with one 'forni of this invention, these high transient vvoltages are substantially reduced, by eliminating the `leaka reactance of the transformer. This l 50 may e accomplished in the case of an output transformer 'of a push-pull .repeater by dividing the primary winding into four sections, two sections being wound on one half of a closed magnetic coreand the' other two sections being wound on the other half. The output circuit of one of 'the push-pull tubes should include the outer sectlon on one half of the core and the inner section on the other half, while the other push pull tube should contain in its output circuit the remaining outer section and inner section. These winding sections should be so connected that they are all aiding for the. signaling currents which ow from one anode to the other anode. Any leakage lines of force which `tend to be created by one section ofthe primary winding due to a change in 'the strength of the space current flowing from the battery to each individual anode. will be neutralized by the primary winding section associated therewith through which the space current flows in the opposite direction. This arrangement prevents the `formation of any apprcciableleakage reactance and consequently prevents the production of large transient voltages which would otherwise be produced.n Y

Referring to the drawings Fig. l is a schematic representation of this invention embodied in a transformer for a push-pull repeater.

Fig. illustrates the manner in which the var1ous windings of the outputtransformer of Fig. 1 may be placed upon al magnetic core.

Fig. ldiscloses a portion of a signaling svstem comprising two line sections 7, -8, in-

terconnecte by -apush-pull repeater, or am- 10. Control electrodes 11 and 12 and cathcdes 13 and 14 are connected to the line section 7 by a suitable input transformer 15, while the anodes 16 and 17 and the cathodes are connected to line section 8 by an output transformer 19. Av source of voltage 20 is connected between the mid point of primary winding transformer c19 and the cathodes for supplying space current to both tubes. In order toprevent lar e transient voltages being produced across t e primary winding of the transformer 19 due, for example, to a sudden blocking of the space current in the tubes 9 and 10 caused, for example, by the 'grids 1l and 12 becoming positive plifier comprising two vacuum tubes 9 and sections 22 and 24- wound on one half of the' core and two other primary winding sections 23 and 25 wound on the other halt.' The secondary winding 26 is wound around the `entire core. 'lhe preferable method of connecting the four primary winding sections 22 to in the output' circuit of tubes 9 and l0 is to connect lead 27 from anode ld to one terminal of section 23," the other terminal ot section 23 by a wire 28 being connected to one terminal of section 2li, which is the'inner section on. the other halt of the core. The other terminal of winding section 24 by a lead 29 is connected to the positive terminal of battery 20. Similarly lead 30 from anode 17 is connected to one terminal ot the outer section 22., while the other terminal of section 22 by wire 32 is connected to one terminal of the inner sectionv25, the other terminal of which by wire 29 is connected to the positive terminal of battery 2G., |lihe individual portion of the output circuit of the tubes 9 and l() therefore includes one inner section and one outer section, wound on dilerent parts of the core structure 2l. Since the'magnetization in winding 23, for example, is exactly neutralized by the magnetization 'of winding 25`through which the 'current from battery 20 is flowing in the opposite direction itis evident that no leakage iux and hence no leakage reaetance will result. Similarly the Ivnagnetizationv of winding 22 is neutralized by the magnetization of the Winding 24. In

order that this neutralization may be substantially complete it is preferable that the four sections'of the primary Winding should all be composed of an equal number of turns. y In one instance where the valueof the source otV voltage 20 was 750 volts the primary winding of an output transformer having appreciable leakage reactanee frequently had developed across its terminals transient voltages as high as three or four-thousand volts, which in several instances was suiiicient to break down `the transformer insulation. These transient' voltages of such a magnitude however are absent when as above described the `transformer is' arranged to have substantially no leakage reactance.' l

The purpose of having one outer section and one inner section on each side of the midpoint of theprimary Winding'is to keep the transformer balanced with respect to natural capacity effects existing between the two windings,-and the core and casing. This arrangement also gives a balanced d. c. resistance.

, lit is obviousthatthis invention is not limmiesen primary winding being composed of four sections ot equal number oi turnss two of said sections being wound on one part of said core, Said two other lsections being wound on another part of saidcore, said primary winding between its external ter# minals comprising a series aiding circuit, being said tour sections connected in the following order: the outer section on one par( of said core. the ,inner section. on the second part of said core, the remaining inner section and the remaining outer section.

2. A repeater transformer comprising a closed magnetic core, primary and secondary' windings? a connection to the mid point of said primary winding, the portion of said primary winding located on one side of said mid point being divided into two equal portions, woundon diiierentparts of said core, the part of said winding on the other side ,of said mid point being wound in two equal portions on diierent parts of said core.

3. In combination'i a push-pull repeater, a line and a transformer for coupling said repeater to said line said transformer having one winding connected to said line and another winding divided into two portions each individual to one of, the elements of said repeater and connected thereto, each portion of said winding being divided into a plurality of winding sections, all of the seetionsbeingdisposed relative to one another such that the leakage reactance is reduced substantially to zero between the two portions of said winding that are respectively individual to said repeater elements.

4. A transformer comprising a magnetic core, a primary winding, a secondary winding', a tap to t emid point of said primary winding, each part of said' primary winding between said tap and one side terminal being divided into an even number of sections wound on diierent parts of said core.

5. In combination, a push pull repeater having electron emitting means and aplurality of anodes, an output transformer therefor comprising a magnetic core, a primar winding, a secondary winding, a connection from said l electron means to the mid point of said primary Winding, a connection from each of said anodes to an outside terminal of said primary winding, the portion of said primary winding located be-V tween each outside terminal and said mid polnt connection being divided into two equal sections wound on different parts of said core and respectively overlaid whereby the leaka e reactancebetween said two portions of t e primary winding is minimized.

6. In combination, a repeater comprising a plurality of space discharge paths having spacial electrodes arranged in push-pull relation, an'incoming line, an outgoing line and circuitsl for associating said paths with one of said lines comprising a circuit branch individual to each ofA said discharge paths and a transformer having a closed core and having a winding connected to the respective line and a second Winding divided into two portions each of which isconnected in one of said individual circuit branches, each of said portions being divided into a plurality of winding sections, certain sections of each winding portion being disposed symmetrically on each side of certain sections of the other winding portion and in close proximity thereto whereby the leakage between said winding portions is reduced substantially to zero.

7. A transformer comprising a magnetic core, a plurality of windings, one of said windings being composed of four sections of equal number ofturns, two of said sections being wound on one part of said core, said two other sections being wound on another part of said core, said winding between its external terminals comprising a series aiding circuit` said four sections being connected in the following order: the outer section on one part of said core, the inner section on the second part of said core, the remaining inner section and the' remaining outer section.

In witness whereof, I hereunto subscribe my name this 20th day of October, A. D.,

WILLIAM J. SHACKELTON. 

